INSECT LIFE IN INDIA AND HOW TO STUDY IT. 



171 



Insect foes of the crop pest may increase in greater numbers when they 

 find their food so plentiful, and in time they reduce the pest to its pro- 

 per proportions again. 



The above short notes will show that it is not difficult to find somo 

 of the homes of the InseGt Life in India. The study of it will require 

 oareful observation and much patience, and whilst training the eye to 

 observe, will develop the faculty of reasoning and working out results 

 as well as, and one would think as usefully as, the most abstruse 

 problem in mathematics. 



Chapter II. 



Structure of Insects. 

 Before proceeding to a consideration of the various Orders into which 

 the class Insecta is divided, it will be necessary to consider shortly here 

 the different parts of an insect. We have already seen that it may 

 have four stages in its life, — the egg, larva or grub, pupa or nymph 

 (chrysalis in butterflies, &c.) and the imago or adult insect (see Fig. l,a, 

 b, c, d). An adult Insect consists of three main divisions, — the head, the 

 thorax, and the abdomen (Fig. 2). The head bears the mouth parts con- 



Fzg, 2. — The North-West or Migratory Locust of India (.Acridium peregrinuni). 

 a, head ; b, mouth parts ; r, compound eye ; d, ocellus or simple eye ; e, 

 antenna ; /, prothorax ; g, mesothorax ; h, metathorax ; i y segments of 

 abdomen ; j, appendages ; k to p, leg — h, coxa (hip) ; I, trochanter ; •», 

 femur (thigh) ; w, tibia (shank) ; o, tarsus ; p, claw. 



sisting of either a biting or sucking mouth or a combination of the two. 



These different forms will be shortly considered since they are of great 



•importance, firstly, as being a feature by which Insects are classified; 



2 



